Google Open Softphone - free Java softphone, running on Linux and Windows. “The phone is tailored to be used in a Callcenter environment based on asterisk. It currently lacks a few features which a home user would expect. Most importantly these are SRTP and NAT traversal”.

“Project SCUPA is about developing extensions and add-ons for Microsoft Communicator 2007 R2. SCUPA enables users to initiate calls via desktop IP phones by selecting contacts in the communicator menu. Except for the Nortel/Polycom Tanjay, phones cannot be directly accessed from the Communicator application, a user therefore cannot initiate a phone-based VoIP call to an OCS contact from within Office Communicator. In our view, this lack of functionality severely hampers the usability of all other phones in an OCS environment. We have therefore developed an extension for Office Communicator 2007 R2 that enables call initiation with IP phones from within the application. In the first version, the extension is designed exclusively for the SNOM brand of IP phones.

There is no status display, whether a person is willing to accept calls, which is a standard feature for Unified Messaging systems ( “Availability” / “Kommunikationsbereitschaftsanzeige” ).

There is no way to encrypt communications on ISO Layer 2, where it would be useful. On the other hand, Microsoft with its properitary protocols encrypt communications on ISO Layer 3 ?! There are 3 different ways to encrypt communications, Microsoft choose one of it.